1. Technical Field
The present invention relates to relational queries for data from different and diverse data sources, including non-relational data sources.
2. Discussion of the Related Art
The technique of SQL federation is used to integrate diverse data sources into a relational database system while allowing those sources to retain their individual identities. It can be an essential component of a successful information integration strategy. While the ideal is a seamless integration, in reality this is not always possible. As data sources diverge from the relational model (e.g., non-relational data sources such as XML files, real time web services, etc.), it becomes progressively more difficult to adapt them.
Data sources that deviate from the relational model present a number of challenges to SQL federation. One of the most problematic, due to its unpredictable nature, is that some syntactically valid queries may not be answerable by a relational engine, because the data source imposes non-relational semantics, such as dictating the order in which operations may occur.